Fuel injectors for controllably metering fuel to the combustion cylinders of internal combustion engines are well known. For ease and reliability in manufacturing, the fuel injectors typically are mounted by their inlet ends at appropriate intervals into a rigid fuel supply line harness, appropriately configured to place the injection end of each fuel injector into its corresponding injection socket in the manifold runner. Such a harness is known as a fuel injector rail, or simply a fuel rail.
In a typical direct injector fuel injection system, each injector is programmed to pulse or open every other revolution of the engine crankshaft. During an injector opening event in a direct injector fuel injection system, the measured fuel pressure in the fuel rail can instantaneously drop by more than 30 kPa, then can increase by more than 50 kPa after the injector closes. Although such high and low pressures can vary widely depending on rail volume, injector open/close time, and inlet line inner diameter, for example, in a typical four cylinder engine operating at 2000 RPM, the combined injectors can pulse at a rate of 66 pulses per second. In such injector-based systems, these pulses cause high frequency pressure waves of significant amplitude to propagate through the fuel rail(s) potentially causing erratic delivery of fuel to the cylinders.
The fuel rails themselves are typically bolted to the cylinder head. In one prior art design, the fuel rail is laterally offset from the position of the bolts which are secured to the cylinder head through brackets. The fuel rail is offset so the bolts are accessible when attaching or removing the fuel rail from the cylinder head. In this design, the brackets extend around a respective fuel injector socket, into which the inlet ends of the injectors are placed. This prior art design requires a jump tube leading from the rail to the respective injector socket.
One known method for reducing injector pressure pulsations is to include a restriction orifice in the fuel line leading to the injector. Due to the narrowing of the flow area, the restriction orifice breaks up and thus reduces the pressure pulsations. The location of the restriction orifice should be somewhere between the fuel rail and injector. In one known design, the restriction orifice is placed inside the jump tube. While this method is effective at reducing pressure pulsations, it also adds cost and complexity to the fuel system.
It would therefore be desirable to have a design and method for reducing pressure pulsations in a fuel line that does not increase cost or complexity to the system.